Characterization of a Silk‐Resinified Compact Fabricated Using a Pulse‐Energizing Sintering Device

Pulse electric current sintering is used to prepare a compact from resinificated hydrous silk powder. Compacts with no remnant silk powders are formed with 20 wt% added water, 20–40 MPa molding pressure, and >353 K molding temperature. The latter two are much lower than those used for conventional hot pressing. No dependence on molding pressure and temperature are found in XRD or FT‐IR analysis, except for a compact molded at 473 K, for which silk fibroin decomposition is confirmed by DSC, EGA‐MS, and molecular weight measurements. The compact's three‐point bending strength depends on the molding temperature, except for the temperature at which silk fibroin decomposes. The maximum three‐point bending strength resembles that of general‐purpose epoxy resin and is much higher than that of PLA.

     

Rapid In Situ Synthesis of Spherical Microflower Pt/C Catalyst Via Spray‐drying for High Performance Fuel Cell Application

A facile route for the rapid in situ synthesis of platinum nanoparticles on spherical microflower carbon has been developed. An aqueous precursor slurry containing carbon black, polystyrene latex (PSL), polyvinyl alcohol, and platinum salt was spray‐dried, followed by calcination to simultaneously reduce platinum salt and to decompose PSL particles. Prepared Pt/C catalyst showed high‐performance electrocatalytic activity with excellent durability. The mass activity and specific activity values were 132.26 mA mg^–1 Pt and 207.62 μA cm^–2 Pt, respectively. This work presents a future direction for the production of high‐performance Pt/C catalyst in an industrial scale.     

NR5A1 is required for functional maturation of Sertoli cells during postnatal development

The orphan nuclear receptor steroidogenic factor 1 (NR5A1 (SF-1)) is expressed in both Sertoli and Leydig cells in the testes. This study investigates the postnatal development of the testes of a gonad-specific Nr5a1 knockout (KO) mouse, in which Nr5a1 was specifically inactivated. The KO testes appeared histologically normal from postnatal day 0 (P0) until P7. However, disorganized germ cells, vacuoles, and giant cells appeared by P14 in the seminiferous tubules of KO but not control mice. Expression of NR5A1 and various factors was examined by immunohistochemistry (IHC). The number of NR5A1-positive Sertoli cells in the KO testes was lower compared with controls at all the developmental stages and decreased to nearly undetectable levels by P21. IHC for anti-Müllerian hormone and p27, immature and mature Sertoli cell markers, respectively, indicated a delay in Sertoli cell maturation in the KO testes. The number of Sertoli cell-expressing factors involved in Sertoli cell differentiation including WT1, SOX9, GATA4, and androgen receptor were lower in the KO testes compared with controls. Furthermore, fewer proliferating cell nuclear antigen-positive proliferative germ cells were observed, and the number of TUNEL-labeled cells was significantly higher in the KO testes compared with controls at P14 and P21, indicating impaired spermatogenesis. IHC for CYP11A1 (SCC) indicated the presence of steroidogenic Leydig cells in the interstitium of the KO testes at all stages examined. These results suggest that NR5A1 is essential for Sertoli cell maturation and therefore spermatogenesis, during postnatal testis development.     

Comprehensive evaluation of leukocyte lineage derived from human hematopoietic cells in humanized mice

Recently, humanized animals whereby a part of the animal is biologically engineered using human genes or cells have been utilized to overcome interspecific differences. Herein, we analyzed the detail of the differentiation states of various human leukocyte subpopulations in humanized mouse and evaluated comprehensively the similarity of the leukocyte lineage between humanized mice and humans. Humanized mice were established by transplanting human CD34(+) cord blood cells into irradiated severely immunodeficient NOD/Shi-scid/IL2Rγ(null) (NOG) mice, and the phenotypes of human cells contained in bone marrow, thymus, spleen and peripheral blood from the mice were analyzed at monthly intervals until 4 months after cell transplantation. The analysis revealed that transplanted human hematopoietic stem cells via the caudal vein homed and engrafted themselves successfully at the mouse bone marrow. Subsequently, the differentiated leukocytes migrated to the various tissues. Almost all of the leukocytes within the thymus were human cells. Furthermore, analysis of the differentiation states of human leukocytes in various tissues and organs indicated that it is highly likely that the human-like leukocyte lineage can be developed in mice.     

Comparative characterisation of dioxane-soluble lignins released by ball milling and by sheep digestion from forage grasses

Faecal soluble lignin (FSL), extracted from the faeces of sheep that received orchardgrass and timothy, were compared with 90% dioxane-soluble lignins released by ball milling (MHL) and by subsequent enzymatic hydrolysis (EHL) from the same grasses. FSL contained much less carbohydrate and esterified p-coumaric and ferulic acids than MHL and EHL. Although no considerable differences were found in the yields of vanillin and syringaldehyde produced by nitrobenzene oxidation, the molar ratio of syringaldehyde to vanillin was higher for FSL than for MHL and EHL. Such differences in chemical properties among the lignin preparations were confirmed by ¹³C-NMR spectroscopy. FSL had a lower molecular size compared with MHL and EHL. Results indicated that syringyl-rich lignin fragments with less phenolic acid esters, probably depolymerisation products of the grass lignins, were released by digestion in sheep from the forage grasses.     

Identification of Aloe species by random amplified polymorphic DNA (RAPD) analysis

Juice and integument of leaves of 3 Aloe species, Aloe vera, A. ferox and A. africana, are not allowed to be used as food according to the Pharmaceutical Affairs Law in Japan. On the other hand, whole leaves of A. arborescens can be used as food. The present study was designed to distinguish Aloe species by random amplified polymorphic DNA (RAPD) analysis. DNA was isolated from fresh and dried leaves of the 4 Aloe species. Five out of 32 different 10-mer primers examined were useful for analysis. By comparison of the characteristic bands of PCR products on agarose gel, it was possible to distinguish the 4 species. Thus, the botanical species of Aloe in commercial food products can be identified by RAPD analysis.     

Selection of acid tolerant bifidobacteria and evidence for a low-pH-inducible acid tolerance response in Bifidobacterium longum

Acidity is an environmental condition commonly encountered by lactic acid bacteria and bifidobacteria in the gastrointestinal tract and fermented foods. In the present study, 22 strains of Bifidobacterium were screened for acid tolerance in artificial gastric juice (AGJ, pH 3.0) and fermented milk. AGJ tolerance was found to be strain-specific, with a pronounced variation among the strains. Several strains with a high survival rate in AGJ that belonged to Bifid. longum, Bifid. breve and Bifid. adolescentis were selected. Among them, only strain BL1 of Bifid longum was found to possess a high survival rate in fermented milk during refrigerated storage. Strain BL1 exhibited a survival rate of more than 25% in AGJ at pH 3.0 for 2 h and maintained a viable cfu level of more than 10(8) per gram of product in fermented milk (pH 4.6) under refrigerated conditions for 2 weeks. The acid tolerance of strain BL1 was found to depend on the final growth pH (<4.5). Rapid loss of acid tolerance was observed when the cells were shifted from acid to neutral conditions by addition of NaOH. Strain BL1 cells were able to maintain much higher intracellular pH under acid conditions, in comparison with those of AGJ sensitive mutant (BL1-S) or cells that lost acid tolerance following pH shifting from acid to neutral conditions. These results suggested that a cytoplasmic pH homeostasis system may function in the acid tolerance response in this strain.     

Growth optimization of thraustochytrid strain 12B for the commercial production of docosahexaenoic acid

High yield of cell, lipid, and docosahexaenoic acid (DHA) from thraustochytrid strain 12B were achieved without the use of a complex medium and at low NaCl concentration which is detrimental to avoid unnecessary corrosion of steel tank equipment during cultivation. Culture medium that contained only 0.1% NaCl and 1% MgSO₄ in an organic base solution containing 8% glucose, 1% yeast extract, and 1% peptone, referred here as NM medium, was found to be as good as or superior to the culture medium prepared from 50%(v/v) seawater with percentage lipid/dry cell weight (DCW) of 66.4%(w/w) and DHA yield up to 43.95 mg/g DCW for the thraustochytrid strain 12B. The NM medium was also applicable to the prominently high DHA-accumulating Schizochytrium limacinum SR21, and therefore this medium could probably be used for other thraustochytrid and other types of microbial strains as well.     

Unipolar Charging of Nanosized Aerosol Particles Using Soft X-ray Photoionization

A unipolar charging device based on a soft X-ray (<9.5 keV) photoionization was developed to investigate the charging efficiency of aerosol nanoparticles. Unipolar charging using a 241 Am charger was also evaluated as a comparison with the characteristics obtained by X-ray charging. The production rate and the concentration of ions generated by the X-ray and 241 Am unipolar chargers were estimated from ion current measurements. Theoretical calculations by the unipolar diffusion charging theory were also carried out and the calculated data were compared with the experimental results. For acquiring a high number of standard nanoparticles, the classification of monodisperse nanoparticles from polydisperse aerosol particles using the X-ray unipolar charger and a differential mobility analyzer (DMA) was also evaluated. The ion production rate of the X-ray unipolar charger was at least 5.5 times higher than that of the 241 Am unipolar charger and the ion concentration was about three times higher. Therefore, the X-ray unipolar charger showed a higher capability for charging aerosol particles of 10-40 nm size in diameter than the 241 Am charger. The charging state of particles produced by the X-ray unipolar charger was in good agreement with theoretical calculations. The X-ray unipolar charger developed herein has potential for use in charging a high number concentration of nanoparticles for use in nanotechnology investigations.     

Effect of leakage current through ferroelectric and insulator on retention characteristics of metal-ferroelectric-insulator-semiconductor structure

Abstract

Retention characteristics of MFIS (metal-ferroelectric-insulator-semiconductor) structures have been investigated theoretically and experimentally. The simulated retention characteristics have indicated that reducing current through the ferroelectric layer is very effective to make the retention time long. In order to reduce the current through the ferroelectric layer, an MFIS with an improved ferroelectric layer and an M-I-FIS (metal-insulator-ferroelectric-insulator-semiconductor) have been investigated theoretically. Both of them have given good retention characteristics. Experimentally, retention characteristics of MFIS have been much improved by annealing, which is considered to suppress the current density in the ferroelectric layer, although those of M-I-FIS have been improved a little.